You are absolutely right, if we worry about what may happen tomorrow, we have worried in vain.
Only sometimes, when something is very scary, or when massive things happen, sometimes it automatically becomes worrying. But then it would be nice if it were carefree again as soon as possible and we'd get straightened out.. Because then we are relaxed and happy and in life in the now. If we can not calm down at all, then we can sleep for a while, then people do exactly what is refreshing, reviving and wholesome.
Your quotes are all wise and beautiful, quotes-haven :D